I think Alex was being a smarty pants. =P Get another motherboard and SLi both.
Mettalic,
This is not uncommon that on-board graphics will not run a game, even if it meets or exceeded the minimum game requirements. For this, I am sorry, your going to have to wait it out. For your new card to get in. Unless the game maker can help you. In my experience, they ignore some on-board graphic chip sets, just do not function with the game, or vise versa. If there was another solution, I would be very much more than happy to pass it along. Unfortunately, this is all I can offer. Beside a little insight what is going on.
You do not have a graphics card. SiS to my recollection never made a full blown dedicated card. Just on-board chipset solutions for motherboard makers. You have a graphics chip set. The difference being. One is intergrated on the motherboard itself and utilizes the same resources for the rest of the system.
Another is a dedicated add-on card, that is easy to spot. It is a card in the lower portion of the board. That has a dedicated graphics subsystem via(not Via chipsets) it's own hardware. The big thing is dedicated RAM for card, not sharing system RAM like an on-board chip set. If your missing RAM somehow, It is a big give away your using an on-board graphics chipset. i.e. - missing 64 megs of RAM out of your 512 or 1024 megs of installed RAM. If you have a add-on card, you show most if not all of the system RAM being reported at 512 or 1024, depending how much you have installed.
To sum all this. Your best bet is to play the game that does work, until your new parts come in.